Silencer



Jan. 28, 1941. J. G. BLANCHARD SILENCER Filed Dec. 3, 1958 4. A :A Y2.,w Illy! MNHN..

Patented Jan. 28, 1941 UNITED STATES SILENCER Joseph George Blanchard,London, England, assignor of one-half to Cecil Gordon Vokes, London,England Application December 3, 1938, Serial No. 243,837

In GreatBritain December 9, 1937 9 Claims.

This invention relates to silencers for the passage of gaseous currents.

It is an object of the invention to provide a silencer in which gasesare caused to converge and enter into mutual collision in the immediatevicinity of the mouth of an expansion chamber and to escape, after`collision, in a direction substantially at right angles to the plane orplanes in which they converge.

With the above and other objects in view, the invention consists in theimproved combinations and arrangements contained in the embodiments nowto be described in detail, and features of which are set out in theclaims which follow.

In the drawing:

Figure l is a longitudinal sectional view of an exhaust silencer for aninternal combustion engine.

Figure 2 is a cross section of same on the line 2-2 of Figure l, lookingin the direction o! the arrow.

Figure 3 is a detail cross section through the member 9, on the line 3-3of Figure 1.

` Figure 4 is a detail crossv section through the member I0, on the line4-4 of Figure 1.

The silencer shown comprises a collision unit mounted within a. vacuumchamber.

The collision unit comprises hollow outer and inner members I and 2respectively, of which the outer member I has a frusto-conical portion 3connected at its base to a portion 4 which is defined chiefly by asurface of revolution formed by an arc revolving about the axis of thefrustum. The portion 4 is formed with a central aperture 5 which isshown as of diameter very slightly larger than the internal diameter ofthe small end of the frusto-conical portion. but, though this ispreferred, it might be of equal diameter.

The inner member 2 has a conical portion 6, of base angle smaller thanthat of the Irustoconical portion 3, and a portion I somewhat similar tothe portion 4 of the member I and provided with a central aperture 8 ofsubstantially the same size as the aperture 5.

The member 2 is mounted concentrically within the member I by means oflugs 9 and I0, of which the latter at least are of streamline form.

In use, the outer member I receives exhaust gases at its smaller end byway of an extension VII forming an inlet pipe. The gases envelop theinner member and traverse the annular path of varying cross-sectionaldimensions formed between the two members, changing direction in thepart ci the path formed between the portions 4 and 1 to enter thecylindrical space or zone sltuated between the apertures 5 and 8, wheregeneral collision occurs between gas particles converging upon the axisof the silencer from all sides as viewed along the axis. After collisiongases may pass into the interior of the inner member by way of theVaperture 8 and out through the aperture 5 of theouter member, the pathsfollowed by the gases in passing in veither direction forming iigures ofsubstantially conical or cylindrical shape coaxial with the axis of thecollision zone. The interior of the inner member acts as a sort ofcushioning chamber, and the majority of gases will pass, immediatelyafter collision, through the aperture 5. The streamlined lugs I0 are,however, hollow and provide paths whereby the pressure within the member2 may be relieved when pressure peaks occur.

The relative shapes and dimensions of the inner and outer members arepreferably such that the annular path between them is of substantiallyconstant cross-sectional area throughout its length: this ensures thatthere is substantially no reduction in the speed of the gases due toexpansion with corresponding reduction of the energy available forcollision.

The vacuum chamber is formed by a casing I2 which surrounds and extendsbeyond the outlet end of the collision unit.

A frusta-conical tube I3, which is secured to the portion 4 of themember I and, by lugs II, to the casing I2. projects, at its smallerend, into the largerend of another frusto-conical tube I4 and receivesthe gases which pass through the aperture Stafter collision.

The tube I4, which is secured to the tube I3 by lugs I5, delivers thegases to an exit pipe IB and the gases exert an injector eilect upon theinterior of the casing I2, by way of the annular space between the tubesI3 and I4, with the result that a vacuum is formed within the casingsurrounding the collision unit, the silencing eiect of the latter beingthereby augmented.

In the silencer just described, the gases enter the collision zone ofthe collision unit by Way of a single aperture which surrounds the zone:since the arrangement illustrated might be modified so that the gasesenter the collision Zone from a plurality of, paths or apertures formed,for example, by partitions in planes parallel or inclined to thelongitudinal axis of the silencer, the term a'path as used in the claimsis intended to include cases in which the gases travel by an equivalentarrangement of paths Further the arrangement is such that the gasesconverge upon the axis of the collision zone in a plane at right anglesto the axis but the term from opposite directions is used in the claimsto include cases in which the gases travel in planes slightly inclinedeither forwardly or backwardly with respect to the axis.

A single collision unit similar to that described above has been foundto provide a satisfactory degree of silence for the exhaust ofaninternal combustion engine but it maybe desirable in some cases, tocombine two or more collision units. Thus, two or more units for causingcollision in the manner described may be arranged in series or inparallel in a common casing.

It is to be understood that the above specific descriptions of silencersfor the passage of gaseous currents have been given by way of exampleand that various modifications may be made without departing from theinvention.

I claim:

1. A silencer or silencer unit for the passage of gaseous currentscomprising a hollow body having an inlet at one end, and a second hollowbody within the iirst hollow body and spaced therefrom to provide anannular passage leading from the inlet, the walls of hollowbodiesdefining the annular passage being turned inwardly at the end remotefrom the inlet to define a circumferential slot surrounding thelongitudinal axis of the hollow bodies, whereby gases passing from theinlet through the annular passage are caused to iiow inwardly towardsthe longitudinal axis of the silencer from all radial directions formutual collision and subsequent dispersal in both directions along thelongitudinal axis.

2. A silencer or silencer unit for the passage of gaseous currentscomprising an inner hollow member closed at one end and having anopening at the other end in a plane at right angles to the axis of thebody, an outer hollow member open at both ends surrounding this innermember and spaced therefrom, the opening in this outer member at the endadjacent to the open end of the inner member being of substantially thesame diameter as the opening in the inner member and in a plane parallelto but spaced from the plane of the opening in the inner member, theopening in the other end of this outer member lying in a plane at rightangles to the axis of the unit adjacent to the closed end of the innermember and an '.nlet tube surrounding this last mentioned opening in theouter member.

3. A silencer or silencer unit for the passage of gaseous currentscomprising an inner hollow member closed at one end and having anopening "aft the other end in a plane at right angles to the axis of thebody, an outer hollow member open at both ends surrounding this innermember and spaced therefrom, the opening in this outer member at the endadjacent to the open end -of the inner member being of substantially thesame diameter as the opening in the inner member and in a plane,parallel to but spaced from the plane of the opening in the innermember, the opening in the other end of this outer member lying in aplane at right angles to the axis of the unit adjacent to the closed endof the inner member, an inlet tube surrounding this last mentionedopening in the outer member and hollow lugs spacing the open end of theinner hollow member from the adjacent end of the outer member, theselugs being circumferentially arranged around the openings in this end ofthe inner and outer members and providing passages connecting theinterior of the inner hollow member with the outllde of the unit.

4. A silencer or silencer unit for the passage of gaseous currentscomprising a hollow conical member having an opening in the basethereof, an outer member enclosing the conical member and spacedtherefrom, this outer member having a frusta-conical portion of whichthe smaller end is adjacent to the apex of the inner conical member andhaving in its larger end an opening of substantially the same diameteras the opening in the base of the conical member, this end of the outermember being spaced longitudinally from the base of the conical memberso as to form therewith a circumferential passage through which gas maybe directed inwardly from all radial directions and an inlet membersurrounding the small open end of the outer member.

5. A silencer or silencer unit for the passage of gaseous currents asdeiined in claim 4 in which hollow lugs are arranged between the base ofthe conical member and the adjacent end of the outer member, thesehollow lugs being spaced circumferentially around the opening thereinand providing passages connecting the interior of the cone with theoutside of the unit.

6. A silencer or silencer unit as defined in claim 4 in which the angleof taper of the frustoconical portion of the outer member is so relatedto the base angle of the inner conical member that the annular pathformed between the inner and outer members is of substantially constantcross-sectional area.

'7. A silencer comprising in combination a silencer unit comprising ahollow body having an inlet at one end, and a second hollow body mountedwithin the nrst hollow body and spaced therefrom to provide an annularpassage leading from the inlet, the walls of these hollow bodiesdefining this passage being turned inwardly at the end remote from theinlet to define a circumferential slot surrounding the longitudinal axisof the hollow bodies, a chamber surrounding this unit and extendingbeyond the outlet therefrom and means within this chamber whereby avac'- uum is formed in the chamber bythe injector or entraining eifectof gases passing longitudinally of the chamber after mutual collisionwithin the zone of the silencer unit surrounded by the aforesaidcircumferential slot.

8. A silencer for the passage of gaseous current comprising an innerhollow member closed at one end and having an opening at the other endin a plane at right angles to the axis of the body, an outer hollowmember open at both ends surrounding this inner member and spacedtherefrom, the opening in this outer member at the end adjacent to theopen end of the inner member being of substantially the same diameter asthe opening in the inner member, and in a plane parallel to but spacedfrom the plane of the opening in the inner member, the opening in theother end of this outer member lying in a plane at right angles to theaxis of the unit adjacent to the closed end of the inner member, aninlet tube surrounding this last mentioned opening in the outer member,a casing enclosing the outer member and extending beyond the outlettherefrom and injector means whereby gases after passage from the outletof the outer member tend to form a vacuum within the casing.

9-. A silencer for the passage of gaseous currents comprising an innerhollow member closed at one end and having an opening at the other endin a plane at right angles to the axis of the body, an outer hollowmember open at both ends surrounding this inner member and spacedtherefrom, the opening in this outer member at the end Vadjacent to theopen end of the inner member being of substantially the same diameter asthe opening in the inner member and in a. plane parallel to but spacedfrom the plane of the opening in the inner member, the opening in theother end of this outer member lying in a piane at right angles to theaxis of the unit adjacent to the closed end of the inner member, aninlet tube surrounding this last mentioned opening in the outer member,a casing'enclosing the outer member and extending beyond the outfiettherefrom, said casing being closed at each end and having an outlet inthe end remote from the inlet tube, a frusta-conical member within thechamber surrounding this outlet and a second truste-conical membersurrounding the opening in the end of the outer member and enteringwithin the end of the first Irusto-eourcal mem.- ber in spaced relationthereto. Y

J GEORGE-BLANCHARD.

